Hi,
I'm quite new to the ardupilot system (and model plane controlling in general) and work together with a group of 9 students at the technical university of Graz on project where we have to build up an autonomous flying plane. Everything is working so far and we use the standard Pixhawk package like external GPS+Magnetometer, AirSpeed sensor and telemetry system (433MHz) - everything from 3DR. The remote controle is an spektrum DX6i connected via standard spektrum receiver to the Pixhawk - Now we switched to the Satellite reciever but haven't tested this yet.
We did our successful first flight in manual mode and used qGroundcontrol do calibrate all the sensors and change parameters (running on Linux). So far so good but when we set our first waypoints and wanted to switch to auto-mode the plane immediately turned upside town and tried to continue flying in this way. Of course that's not what we wanted to and already crashed it once when we tried to turn it back manually.
Does anyone have an Idea what could be the reason for that. We have checked a lot of parameters and couldn't find any that might be the reason for that behaviour - Do you know why?
Thanks,
Max
Replies
Hello,
I had the exact problem with my plane (Skywalker/Aero with Pixhawk and APM:Plane 3.3.0), I hand-launched it directly in AUTO mode and after a couple of seconds gaining altitude it went UPSIDE DOWN all of a sudden and kept going like that... unbelievable. I lost sight of it and tried to bring it back with RTL but ended up crashing it -totally destroyed-.
I've checked all the possible causes you've posted and I haven't found a definite answer as to what the problem was:
-INVERTEDFLT_CH is disabled (0)
-I can't arm it anymore as it is quite destroyed right now, but prior to the flight I had tested that everything was working alright in STABILIZE mode (moving the plane manually and seeing how it counteracted the movement), which I believe it's equivalent to the tests you refer to in FBWA or loiter.
-Pixhawk is for sure pointing forward and right-side-up, AHRS_orientation parameter is set as it should (0).
So I'm stuck at finding the reason why it flew upside down. I'm afraid that the rudder reversal could be set incorrectly, it is: RC4_REV,-1, while on other identical plane I have its value set to 1. Moreover the wiki says:
http://plane.ardupilot.com/wiki/arduplane-setup/first-time-apm-setu...
Could that have been the reason for the plane to fly upside down? Here are the plane's parameter list and log files for that flight in case anyone wants to take a look:
https://drive.google.com/folderview?id=0B9G60cFGY26ffkZYN184ZlVXUGF...
Thank you very much for your help.
Indeed BOTH the rudder AND the ailerons were set reversely, that caused the plane flying upside down as soon as it started the mission.
Sorry for my late reply. You are right, in this case you have to invert the directions for ailerons and rudder and then invert on the rc as well. It can be easily tested on the ground when switching to an auto mode and turn the plane. Then it should controls the ailerons and rudder to act against the turn.
Max
Yes, I will thoroughly check it from now on. In this case since both ailerons and rudder were reversed I didn't notice the issue in the quick -bad- checks. Thanks a lot for the reply and tips!
Does this happen in FBWA or loiter? It sounds like the pixhawk thinks it's inverted. Check the AHRS_orientation parameter.
It happens when switching from manual to auto flight mode when the plane is heading tot the first waypoint. And I think the ailerons are steering in the wrong directions as well, when setting the plane to ALTCTL mode and rolling it.
If you haven't gone through the entire wiki yet, I'd suggest doing so. Here's the page on setting up a flying wing type craft.
http://plane.ardupilot.com/wiki/arduplane-setup/first-time-apm-setu...
I think that's exactly the procedure I have to walk through - I'll try this
Check the orientation of the pixhawk in the frame. Make sure it's pointing forward and right-side-up.
You probably need to select "reverse" on the pixhawk for your ailerons.
The best way to test this is (with the motor disabled) by arming the plane on the ground and selecting FBWA mode. As you manually move the plane around, the control surfaces should move to counteract that motion. For example pitching the nose down should make the elevators go up. Banking to the left should make the right aileron go up. Yawing to the left should make the rudder go right.
If those things are not happening, reverse channels as needed in the pixhawk settings. You use the reversing functions on your transmitter to make manual mode work right, then use the ones in the arduplane firmware to make auto modes correct.
According to:
http://plane.ardupilot.com/wiki/arduplane-setup/first-time-apm-setu...
It must be one of the ELEVON_REVERSE, ELEVON_CH1_REVERSE or ELEVON_CH2_REVERSE parameter but I can't find them in the parameters of my plane.
I used qgroundcontrol to upload the firmware for our pxhawk and only have the parameter as shown (when export with qgroundcontrol) here:
https://pixhawk.org/firmware/parameters
Some questons I still ask myself (as a newbie):
Don't I use the arduplane firmware, instead do I use the PX4 firmware?
Do I need Missionplanner to run APM:PLANE on my device?
When I install the firmware via source and I do "make px4-v2 & make px4-v2-upload" in the ArduPlane folder - Do I compile and upload the PX4 or Arduplane firmware?
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